Mechanical mallet



Nov. 9, 1937. H. D. GREENBERG MECHANICAL MALLET Filed Feb. lO, 1934 w \WEWEQTEWMHEI.. l

S R m YW mm V WM @m Patented Nov. 9, 1937` I UNITED STATES ddd/.4915

MECHANICAL MALLET Harry Daniel Greenberg, New York, N. Y., assignor to Industrial Hammer Development Corporation, a corporation of New York Application February 10, 1934, Serial No. 710,753

13 Claims.

My invention relates to mechanical mallets, and while it is adaptedv for heavy work such as rock drilling, it relates particularly to those used for dental and bone surgery. My mallet pos- Sesses, among other advantages, those of being capable of such adjustment as to cause either a succession of blows, or one blow at a time; of providing for regulating the strength of the blows delivered, without changing the spring by which they are caused; and of simplicity of construction, with accessibility of the parts, and to such ends my invention consists in the improvements in mechanical mallets hereinafter specified.

of my invention, known to me, but such forms are to be regarded as typical, only, of the many embodiments of which my invention is susceptible.

In the accompanying drawing:

2 Fig. 1 is a vertical View partly in section showing a dental mallet embodying my invention.

Fig. 2 is a longitudinal section taken substantially on the line 2*-2 of Fig. 1.

Fig. 3 is a horizontal sectional View taken on the line 3-3 of Fig. 2.

Fig. 4 is a View similar to Fig. 2, but showing the hammer head in raised position, and with the pin I4 released by the blind thread so that the hammer head is free to be thrown downward by the spring 24 to strike a blow on the tool holder.

Fig. 5 is a view similarto Fig. 4 showing the hammer head resting on the head of the tool holder at the end of the stroke.

Fig. 6 is a View similar to Fig. 4 but showing the use of a disc 2'I.

In the form of my invention shown in Figs. 1

to 5, there is a casing I which is closed at its upper end by a ball bearing 2 and at its lower end is closed by a bushing or head 3 which is adjustably mounted in a screw-thread 4 formed in the inner surface of the casing. For the purpose of locking the said head in any desired position up or down in the casing, the latter is provided with a screw thread on its exterior, and a screw sleeve is mounted thereon. When the head 3 has been adjusted to the desired position, it is locked therein by screwing the sleeve I5 hard against a shoulder 3U. on the said head. A toolholder 'I is mounted in a bore 8 in the cylinder head 3 and consists of a preferably cylindrical shank la and a disc-shaped head 1b. The tool holder, in the present instance, is prevented from rotating, by engagement of a notch 'Ic in the periphery of its head Ib with a guide key 9,

I have chosen for illustration the best formsA which is set in, or otherwise attached to the inner periphery of the casing I. The portion of said guide key which is engaged by said head has a shoulder 9a formed on said guide key, to limit the( upward movement of the tool-holder. 5 A mallet-head or hammer head Iii is also mounted in the casing and is prevented from rotation by engagement of said guide key with a groove Illa in the mallet-head. A screw shaft II is mounted at its upper end in the ball-bear- V10 ing 2 and at its lower end in a bore I3 formed in the tool-holder 1, the shaft also extending through a bore I3ct formed in the mallet head. The shaft is provided with a screiwthread I2, which at its upper end becomes a blind- 15 thread, i. e., the channel between adjacent turns of the thread at the upper end becomes rapidly shallower until it merges kinto the slightly enlarged cylindrical surface of the shaft. This is for the purpose of releasing a headed pin I4 which is rotatively mounted horizontally in a hole I5 in the mallet-head Ii), said pin being pressed into said groove and. toward the shaft by a spring I6 that is secured by a screw II in a slot I8 in the mallet-head. 25

. For the purpose of holding pin Ill out of engagement with the screw thread, when it has been retracted therefrom by the said blind thread, so that the mallet-head may be thrown against the tool holder to drive the tool to its 30 work, I provide a latch I9, which is mounted on a latch carrier, that, in the present instance, is in the form of a wire 20 having a vertical portion 2lb, which is located in a vertical bore 2| in the mallet-head, said wire having at its lower end, a head 2Ia between which and the top of the bore is interposed a spiral spring 22, the spring tending to extrude the said wire-head 2Ia below the bottom of the mallet-head. The upper end of said wire is bent horizontally and is located in a slot 23 in the mallet-head, and said wire is provided with a finger 23a or other form of latch, for' the purpose of its dropping behind the head I4a of the said pin I4, when the blind thread raises said pin out of the groove between the threads. Thus the pin is prevented from re-engaging the screw thread until the mallethead has caused the head 2Ia on the lower end of the wire 20 to rise in the mallet-head and release the latch I9. Y

A relatively heavy spring 24 is located between the underside of the top of the casing and the upper side of the mallet-head, for the purpose of throwing the maillot-head to its blow on the tool holder.

The operation of the whole mechanism may now be stated. Supposing, rst, that it is desired to cause the mallet to deliver a succession of blows,-the head 3 is adjusted at a suiciently high level so that the pin I4 cannot fall below the lower end of the screw thread I2,V and the shaft is set in rotation. The said pin, under the pressure of the spring- I6, `dropsinto-theA groove between the threads and is carried 'pwardtheret by until, at the top, the blind thread throws the pin outward until the latch I9 drops behind the head of the pin, when, the mallet-head being free of the screw-thread, the spring'24 `thro-ws the mallet-head downward on the .tool carrierw Contact of the head 2Iaofi1the latchr carrier with the tool holder, causes the former. to rise,`;`

relative to the mallet head, and thus to release the latch I9 from the pin head Illa, when the pin I4, under the tension of the spring I5, reengages the screw thread, and the operation is repeated and will continue so long as the shaft is revolved.

It will be observed thatmy mechanism when used for continuous hammeringdoes not Iequire that the` tool be pressed against the piece or place being operated upon',"such as a'tooth or bone, but depends onlyonthe rotation of the shaft, and on the adjustment of the casing'head ment with said screw thread, a latch and a latchoperating part mounted on said mallet head and -Y "adapted to* catch said part when it is thrown out of engagement with s'aid screw thread, a spring adapted to throw said mallet head when said 3 so as to prevent the pin I4 from falling b'elow the lower end of the screw threa'd'so that it cannot engage saidthread. .Myconstruction therefore, relieves a dental patient, for instance,

`from the discomfort and pain of such` pressure.

It also enables the operator to regulate the nearness of the tool toV the' work that is being hammered, and thus to hammer lightly or heavily as may be best. For instance, Vtile setters, in cutting a tile with a'chisel, hold the. chisel slightly `away from the tile, as otherwise it would break` the tile irregularly.Y My mechanism makes such operation possible.

,When my implement is to be used for delivering intermittenthammr blOws', the casing head 3 is lowered sumciently` so that the pin'I4 will be below the level of the lower end of the screw thread I2 and therefore cannotienga'ge it. This lowering'of the head maybeeffectedby unscrewing the screw sleeve 5A so. as-to unlock` the said casing head, when .thelatter can bescrewed downward from `the casing4 suciently to accomplish the .said purpose, after which. the said screw sleeve mayagain be used toI lockthe casing head in the-desired position. Intermittent blows may now be .effected by. grasping.-.the casing and pressingdown upon .the chiselorother tool, .while the latter rests {inthe-tooth .of a patient, or other object tO-bepperated upon, until the head lb of the `tool holder` has raisedthe. hammer suiciently so that thepin :I4 canwengagethe screw thread. Therotation of the `screw shaft will, as before, raise the hammer untilly thesaidpin has been thrust outwardly and beenfcaught by the latch 23a, when'thespringfM will-throwthe mallet head downward,` striking ablow-. on the tool i holder, where it will'come to rest unlessand until the casing is again `presseddown upon the tool.

The mechanism by whichf-myfvmallet Ahead is casing, a shaft therein having a screw thread automaticallyV reciprocatedf is entirely contained within the mallet-head, so that,'.ibyl'unscrewing the casing head the entire reciprocating mechanism can be taken outfofthe casing forrrepair or adjustment.

The design of my.: machine..v isfsimple and rugged.

Where my invention is applied to mechanical mallets, for heavy work, such as rock drilling, I prefer, in place of the pin I4, to use a disc 21 whose under surface 21a is made conical or beveled so as to rest upon and contact with the upper surface EZa of the screw thread I2, as shown in Fig. 6.

The said disc may be supported in any manner which will permit it to move into 4and out of con tact with the screw thread. In the present instance, I have illustrated it as mounted upon a bracket 5 which is fastened to a spring 26 that 'pin' 28 is pointed at its upper end, and a latch 29 corresponding to the latch 23a of Fig. 1, together with its supporting wire 29, head 2 la, and springV 22, operates to hold the disc 21 out of engagement with the screw thread while the l"hammer is delivering its blow. This disc form of thread-engaging means will be more durable and' require less power than the pin I4.

I claim:

i. In a mechanical mallet, the combination of a casing, a rotatable shaft therein having a screw thread thereon ending in a blind thread, a mallet head having a part thereon for engagepart is held by said latch, a tool holder in'said 'casing which is adapted to receive the blow of said hammer head, and means for so adjusting said tool holderas to permit said hammer head todescend so low that its said thread-engaging part shall be below the range `of engagement of said thread and means whereby said hammer head may be raised suiiiciently so that said part shall engage said screw thread.

2. In a mechanical mallet, the combination of a casing, a shaft therein having a screwvthread ending in a blind thread, a hammer head having a part adapted to engage the said thread, a latch and a latch-operating part carried by said mallet head for holding said part out of engagement with said thread when it has been-thrown out of said engagement and means for so adjusting the range of travel of said mallet head relative to said screw thread asto cause said screw-engaging part to be out of range with said thread.

. 3. In a mechanical mallet, the combination of a Casing. a shaft therein having a screw thread "L ending in a blind thread, a hammer head having a part to engage the said thread, a latch and a latch-operating part carried by said mallet head for holding said part out of engagement with said Vthread when it has been thrown out of lsaid engagement and means for so adjusting the range of travel of said mallet head relative to said screw thread as to cause-said screw-engaging part to be out of range with said thread, and means for so raising said mallet head as to bring said screw` engaging part into engagement with said thread.

4.-' In a mechanical mallet, thercombination of a ending in a blind thread, a hammer head having a part adapted to engage the said thread, a latch and a latch-operating part carried by said mallet head for holding said -part out of engagement with sai-d thread when it has been thrown out of said engagement and means for so adjusting the range 4 of travelof said mallet head relative to said screw thread as to cause said screw-engaging part to be out of range with said thread, and means for so raising said mallet head as to bring said screwengaging part into engagement with sai-d thread, said means comprising a tool holder.

5. In a mechanical mallet, the combination of a casing, a rotatable shaft mounted therein and having a screw thread ending in a blind thread, a mallet-head, a screw thread-engaging part mounted on said head, and means of release mounted on, carried by and movably secured to said mallet-head, whereby said thread-engaging part may be made repeatedly to engage said screw thread automatically to raise said hammer when said hammer strikes the tool-holding member.

6. In a mecham'cal mallet, the combination of a casing, a rotatablev shaft mounted therein and having a screw thread ending in a blind thread, a mallet-head, a screw thread engaging part mounted on said head, means of release mounted on, carried by and movably secured to said mallet head, whereby said screw-engaging part may be made repeatedly to engage Said screw thread automatically to raise said hammer when said hammer strikes the tool-holding member, and means f or so raising said hammer as to bring said screwengaging part into engagement with said screw thread.

7. In a mechanical mallet, the combination of a casing, a rotatable shaft having a screw thread thereon ending in a blind thread, a mallet head mounted in said casing, a rotative thread-engaging part mounted on said mallet head, a latch and latch-operating part carried by said mallet head for holding said part out of engagement with said thread when it has been thrown out of said engagement, and means carried on said mallet head for releasing said thread-engaging part when said mallet head strikes the tool-holder.

8. In a mechanical mallet, the combination of a casing, a rotatable shaft having a screw thread thereon ending in a blind thread, a mallet head mounted in said casing, a rotative thread-engaging part mounted on said mallet head, said part consisting of a disc mounted rotatably upon said mallet head, a latch and latch-operating part carried by said mallet head for holding said part out of engagement with said thread when it has been thrown out or" said engagement, and means carried by said mallet head for releasing said threadengaging part when said mallet head strikes the tool-holder.

9. In a mechanical mallet, the combination of a casing, rotatable shaft therein having a screw thread thereon ending in a blind thread, a mallet head having a part thereon for engagement with said screw thread, a latch and a latch-operating part mounted on said mallet head and adapted to catch said part when it is thrown out of engagement with said screw thread, and adapted to release said part when said mallet head strikes said tool holder, a spring adapted to throw sai-d mallet head when said part is held by said latch, a tool holder in sai-d casing which'is adapted to receive the blow of said hammer head, and means for so adjusting said tool holder as to permit said hammer head to descend so low that its said threadengaging part shall be below the range of engagement of said thread, and means whereby said hammer head may be raised suiciently so that said part shall engage said screw thread.

l0. In a mechanical mallet, the combination of a casing, a shaft therein having a screw thread ending in a blind thread, a hammer head having a part adapted to engage the said thread, a latch and a latch-operating part carried by said maliet head for holding said part out of engagement with said thread when it has been thrown out of said engagement, a means thereon for releasing the said part when said mallet head strikes the tool holder, and means for so adjusting the range' of travel of said mallet head relative to said screw thread as to cause said screw-engaging part to be out of range with said thread.

ll. In a mechanical mallet, the combination of a casing, a shaft therein having a screw thread ending in a blind thread, a hammer head having a part to engage the said thread, a latch and a latch-operating part carried by said mallet head for holding said part out of engagement with said thread when it has been thrown out of said engagement, a means thereon for releasing the said part when said mallet head strikes the tool holder, and means for so adjusting the range of travel of said mallet head relativeto Said screw thread as to cause said screw engaging part to be out of range with said thread, means for so raising said mallet head as to bring said screw-engaging part into engagement with said thread.

l2. In a mechanical mallet, the combinationv of a casing, a shaft therein having a screw thread ending in a blind thread, a hammer head having .a part adapted to engage the said thread,

a latch and a latch-operating part carried by said mallet head for holding said part out oi engagement with said thread when it has been thrown out of said engagement, a means thereon for releasing the said part when said mallet head strikes the tool holder, and means for so. adjusting the range of travel of said mallet head relative to said screw thread as to cause said screwengaging part to be out oi range with said thread, and means for so raising said mallet head as to bring said screw-engaging part into engagement with said thread, said means comp-risingL the toolholder.

13. In a mechanical malle-t, the combination of a casing, a rotatable shaft therein having a screw thread thereon ending in a blind thread, a mallet head having a part thereon for engagement with said screw thread. a latch and a. latch.- operating part mounted on said mallet head adapted to catch said part when it is thrown out of engagement with said screwv thread, a spring adapted to throw said mallet head when said part is held by said latch, a tool hoider in said casing which is adapted to receive the blow of said hammer head, and means for so adjusting said tool .holder as to permit said hammer head to descend so low that its said thread-engaging part shall be below they range of engagement of said thread, and means whereby said hammer head may 'be raised sufficiently so that said part shall engage said screw thread, said last-mentioned means comp-rising a head at the tool end of said casing.

HARRY DANIEL GREENBERG. 

